/* 手机设备区间  320px-750px/768px
          断点: 320px  / 360px /  375px / 414px /540px
        
        */
        @media screen and (min-width:320px) {
            /* 375---100  320---? */
            html {
                font-size: 85.333px;
            }
        }
        @media screen and (min-width:360px) {
            html {
                font-size: 96px;
            }
            
        }
        /* 假设psd设计稿 375px 适配的逻辑像素375px  */
        @media screen and (min-width:375px) {
            html {
                /* 为了好计算 */
                font-size: 100px;
            }
        }
        @media screen and (min-width:414px) {

            html {
                font-size: 110.4px;
            }
            
        }
        @media screen and (min-width:540px) {
            html {
                font-size: 144px;
            }
        }
        
        @media screen and (min-width:750px) {

            html {
                font-size: 200px;
            }
            
        }